Roll Bonding of Two Materials Using Temperature to Compensate the Material Strength Difference

Abstract

A part with optimized material characteristics can be realized by cladding of two or more materials. In the aerospace industry high strength aluminum alloys like AA2024 are commonly used. Due to their susceptibility to atmospheric corrosion a protective surface layer has to be provided, e.g. pure aluminum. Because of high differences in material strength problems occur during bonding. This study discusses if and how active cooling can be used to create a temperature field which compensates the material strength difference and thus improves roll bonding of two materials of different strength. Cooling simulations were carried out to investigate the influence of the boundary conditions and cooling time before hot rolling for different layer thicknesses. For the example of a thick core (50 mm) and a thinner cover layer (10 mm) the optimal cooling time was determined to be in a range of 3 - 14 s. Furthermore, roll bonding experiments were performed at various height reductions and cooling times to investigate the influence of the material strength differences on the rolling and bonding behavior. Due to the implementation of a cooling operation a varying elongation of the surface layer and the core material has been successfully reduced from 30 to 22 mm.